BobbyG

Batteries are powered by chemical reactions. Cold temperature slows the rate of those reactions, and can raise or lower internal resistance depending on the battery type and design. This can lead to low voltage and higher or lower than normal discharge. So then, further depending on your battery and its circuitry and the programming used to ascertain its status...it's a crap shoot.

But generally speaking, cold weather diminished battery performance.

I ride down to 10F and I don't notice it so much in my current lighting set-up which is LEDs and Lithium batteries, both rechargeable and single use), but I do notice it in my phone, which is also lithium battery powered, but I usually carry it in a holster on my hip. I don't know if the cold reduces the charge as much as it says, or if the circuitry is fooled by some other temperature related issues. Either way, when the phone goes into low battery mode out in the cold on a commute, it usually returns to normal as it warms up.

In the old days my main headlight was a halogen bulb driven by a rechargeable lead-acid battery. That battery was definitely affected by the cold. And my cellphone...well, I didn't have one until 1997.